Power consumption of thermal sensors in some current processing systems is a significant component of idle power during low power operations. For example, in deepest package C-states, thermal sensor power consumption is significant, and on some products, thermal sensor power consumption during active may even significantly impact power consumption at maximum frequencies. Thermal sensors are typically left running even in idle states, even though the data is not required during idle states when most of the CPU is powered off.
Thermal sensors are typically left running because they take a relatively long time to scan. In traditional systems, a thermal sensor would need to rescan the temperature(s) from scratch upon exit from a low power state. Current thermal sensor design is an up/down counter that steps one code per 640 ns. With a resolution of 9 bits, maximum scan time can be as high as 2^9*640 ns or 327 us. In some traditional systems, the active time in idle scenarios is <100 us, which means that with such a long scan the system could never achieve a full scan before re-entering the low power state. Thermal telemetry (and control) would potentially lag real conditions indefinitely unless the thermal sensors remain active to keep a valid reading.
Descriptions of certain details and implementations follow, including a description of the figures, which may depict some or all of the embodiments described below, as well as discussing other potential embodiments or implementations of the inventive concepts presented herein. An overview of embodiments of the invention is provided below, followed by a more detailed description with reference to the drawings.